Tuesday, January 26, 2010

The study of honeybees and their social structure can give scientists a greater understanding of how infectious disease spreads among animals and humans, says a Colorado State University professor who has embarked on a five-year study of honeybee behavior, funded by a National Science Foundation CAREER award.

Dhruba Naug, an assistant professor of biology in the College of Natural Sciences, is using the $650,000 grant to investigate how the social organization of bees has evolved in response to the threat of the parasites that infect the colony. At the same time, parasites can also be expected to adapt rapidly to these changes, making it a continuous arms race between the two parties. The grant includes some funds from the American Recovery and Reinvestment Act and also comprises an educational component to get children at the elementary school level more interested in biology and science.

“We are investigating whether we can use the honeybee colony as a model system to understand how diseases spread in a social group,” Naug said. “If you’re talking about the spread of disease in a human community, there is a social context to it. Who infects who is based on various things – what you do, how often you come in contact with other people, how you behave. Bees have a fairly sophisticated social structure, they get a lot of diseases, and they can be subjected to a variety of experimental paradigms - a golden combination for research.”

“What is it about the social structure that allows bees to be tolerant of diseases and what do parasites do to adapt to them?”

His research on diseased bees has produced some interesting results including:

• Bees that carry a disease experience starvation since the pathogens infecting them steal nutrition, leading to changes in their behavior. They are, for example, less willing to share food with other bees and more willing to leave the colony to find food, which may affect the contact structure and even affect honey production.

• Hunger in infected bees also means that they have problems maintaining their temperature; they get colder because they don’t have enough food to burn. As a result, they are likely to move toward the center of the colony for warmth, which is likely to infect more bees.

• The social structure of bees is such that the young individuals and the queen are segregated toward the center of the colony, providing them some amount of immunity from pathogens entering the colony.

“We’re not studying specific diseases as much as we are the transmission of diseases,” Naug said. “Anytime you’re looking at dense populations – such as livestock – you are talking about similar principles of how things spread.” Focusing on general principles that apply to most infectious diseases rather than any specific pathogen is more illuminating in many ways.

Naug, who joined Colorado State University in 2005, teaches undergraduate biology and a graduate course in behavioral ecology. He plans to teach an undergraduate course this fall that will explore how to apply the principles of evolutionary biology to medical science. Understanding more about host-parasite interactions can help doctors tackle such issues as antibiotic resistance.

“When we get a fever, we take a bunch of medicines to lower our temperature. But what if the body is ramping up the temperature to fight the pathogen? Maybe we need to understand the symptoms a little better rather than trying to come up with a chemical to fight every symptom of a disease.”